This invention relates to an electrical connector and more particularly one for use in the human body.
In cochlear stimulating prostheses systems an electrical connector is often placed between the stimulating electrode and the driving component of the prosthesis to allow the driving component to be removed, replaced, or converted to another driving system, without disturbing the electrode itself. This connection and disconnection can be done by either mounting the connector in a channel through the skin (referred to as a percutaneous plug) or by implanting the connector beneath the skin (referred to as a surgical disconnect).
Percutaneous plugs seem to have a limited rather than a permanent life span of usefulness due to the ever present threat of infection through the open skin, and a tendency of the epithelium to bridge beneath such a foreign body and to eject it. Further, a percutaneous plug will usually never be considered in a transcutaneous driving system which emphasizes a fully implanted radio frequency or ultra sonic receiver. In such systems the receiver is implanted under the skin and receives signals from a transmitter located outside of the human body. The transmitter is of course, connected to a transducer and amplifier to convert audio signals into either radio signals or ultra sonic signals which are transmitted through the patient's skin to be detected by a receiver or a transducer connected to an amplifier within the patient's body.
From an engineering standpoint, the surgical disconnect presents unique problems. It must be small yet still easily manipulated by a gloved surgeon. It must be rugged, biologically inert, and should function reliably in a very hostile environment through multiple disconnection and reconnection cycles. For multi-channel systems it must carry fifteen to twenty leads or more.
Pin-type connectors have been succesfully adapted in prior art surgical disconnects for cochlear implant systems. There are, however, some disadvantages with such pin-type connectors. Such connectors involve the use of non-biocompatible metal like beryllium copper. Such copper pins are isolated by gold plate in the expoxy connector housing but some small risk remains. The need to weld or solder the leads to the electrode also adds a potential failure site to the device. And finally, there is a constant desire to reduce the size of any implant.
Still another serious problem is to electrically isolate each of the contacts in the disconnect and prevent water vapor or liquid from causing a short circuit between them.